wpdb::check_safe_collation( string $query ): bool

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$querystring

The query to check.

Return value

bool

True if the collation is safe, false if it isn't.

Performance profile

How much work a call to wpdb::check_safe_collation() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Light

Touches nothing outside its own arguments.

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

4–49

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 57.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

4

4 places in core call this, so the cost is paid more often than your own code shows.

What one call costs · 6 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost wpdb::check_safe_collation() can have, taken from its control-flow graph on PHP 8.5.

Uses · 3

• wpdb::check_ascii()Checks if a string is ASCII.
• wpdb::get_table_from_query()Finds the first table name referenced in a query.
• wpdb::get_table_charset()Retrieves the character set for the given table.

Used by · 4

• wpdb::get_col()Retrieves one column from the database.
• wpdb::get_results()Retrieves an entire SQL result set from the database (i.e., many rows).
• wpdb::get_row()Retrieves one row from the database.
• wpdb::get_var()Retrieves one value from the database.

Source code

View on Trac ↗View on GitHub ↗

3475	protected function check_safe_collation( $query ) {3476		if ( $this->checking_collation ) {3477			return true;3478		}3479 3480		// We don't need to check the collation for queries that don't read data.3481		$query = ltrim( $query, "\r\n\t (" );3482		if ( preg_match( '/^(?:SHOW|DESCRIBE|DESC|EXPLAIN|CREATE)\s/i', $query ) ) {3483			return true;3484		}3485 3486		// All-ASCII queries don't need extra checking.3487		if ( $this->check_ascii( $query ) ) {3488			return true;3489		}3490 3491		$table = $this->get_table_from_query( $query );3492		if ( ! $table ) {3493			return false;3494		}3495 3496		$this->checking_collation = true;3497		$collation                = $this->get_table_charset( $table );3498		$this->checking_collation = false;3499 3500		// Tables with no collation, or latin1 only, don't need extra checking.3501		if ( false === $collation || 'latin1' === $collation ) {3502			return true;3503		}3504 3505		$table = strtolower( $table );3506		if ( empty( $this->col_meta[ $table ] ) ) {3507			return false;3508		}3509 3510		// If any of the columns don't have one of these collations, it needs more confidence checking.3511		$safe_collations = array(3512			'utf8_bin',3513			'utf8_general_ci',3514			'utf8mb3_bin',3515			'utf8mb3_general_ci',3516			'utf8mb4_bin',3517			'utf8mb4_general_ci',3518		);3519 3520		foreach ( $this->col_meta[ $table ] as $col ) {3521			if ( empty( $col->Collation ) ) {3522				continue;3523			}3524 3525			if ( ! in_array( $col->Collation, $safe_collations, true ) ) {3526				return false;3527			}3528		}3529 3530		return true;3531	}

Changelog

Introduced in 4.2.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 6.7.7 tag, from src/wp-includes/class-wpdb.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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